1. Field of the Invention
The present invention relates to filled hardenable resin compositions, and more particularly to hardenable, or setting, two-component resin products containing such compositions for use in systems wherein a filler-containing resin component and a catalyst component are maintained separate from one another until the time of use, and then mixed together to allow ingredients therein to react and form a hardened product, e.g., a grout around a reinforcing member in a hole in a mine roof.
2. Description of the Prior Art
Anchor bolts are employed in various fields of engineering, for example, as strengthening or reinforcing members in rock formations and in structural bodies. The bolts are inserted into drill holes in the formation or body, and often are fixed or anchored therein, at their inner end or over substantially their entire length, by means of a reactive grouting product which hardens around the bolt. When used in a mine roof, bolts grouted in this manner help significantly to prevent mine roof failure. The higher the anchorage strength (dependent on the strength of the grout interface with the bolt and with the wall of the hole), the more reliable the roof support system.
Two-component reactive grouting products which have been used in rock bolt anchoring include those based on hardenable synthetic resins, and these have been introduced into the drill holes through a feed pipe, or in cartridged form. Although the reactive ingredients of the product can be delivered into the hole in combined and mixed form either before or after bolt insertion, usually they have been delivered separately into the hole, e.g., in compartmented cartridges, and combined therein and mixed, e.g., by inserting the bolt into the cartridges and rotating it.
A hardenable synthetic resin composition that has gained wide acceptance as a component of bolt-anchoring grouting products is a composition containing an unsaturated polymerizable polyester resin and a monomeric polymerizable ethylenic crosslinking agent therefor. These materials, together with a polymerization inhibitor or stabilizer, and a promoter for a peroxide catalyst, constitute a resin formulation contained in a first grout component (R). A peroxide catalyst system for initiating the crosslinking polymerization is contained in a second grout component (C), kept separated from component R until the hardening reaction is to take place. When components R and C are combined and mixed, the action of the catalyst causes the crosslinking reaction between the polyester and ethylenic monomer to take place, resulting in a thermoset, hard resin.
Particulate inert fillers or aggregates are nearly always added to the resin component of resin grouting products. Fillers have been reported (e.g., in U.S. Pat. No. 3,731,791, Fourcade et al.) to reduce the shrinkage of the resinous mass which occurs during polymerization, and they also reduce the cost of the product because they replace a portion of the more-expensive resin composition. A variety of materials have been disclosed as fillers, e.g., in U.S. Pat. No. 4,280,943 (Bivens et al.), the disclosure of which is incorporated herein by reference. U.S. Pat. No. 3,371,791 reports that, in order to ensure filler loadings in the 70-80 percent range while retaining adequate fluidity in resin-based compositions, the filler particle size distribution should be from 150 mesh to 300 mesh (0.05 mm to 0.1 mm).
German Offenlegungsschrift No. DE 3033801 A1 describes the use of filler-containing set resin compositions to form shaped articles of various kinds. A high-viscosity unsaturated polyester resin solution, in mixture with a peroxide catalyst and a promoter, and optionally some 0.001-0.5 mm filler, is co-extruded with 0.2-3 mm sand into a mold, where hardening takes place to form the shaped articles.